A commercial truck driver tests positive for marijuana. The driver has a medical marijuana card, a physician’s recommendation and records showing the marijuana came from a state-licensed dispensary.

With the federal government moving some marijuana into Schedule III, can the Medical Review Officer, or MRO, treat that positive test as negative?

The Department of Transportation has answered that question: No.

That answer offers an important lesson for employers navigating changes in federal marijuana policy. Marijuana’s federal status is changing, and a broader rescheduling proceeding remains underway. But Schedule III does not automatically make marijuana permissible for employees in federally regulated safety-sensitive transportation positions.

In December 2025, President Trump signed an Executive Order directing the Attorney General to expedite the federal rulemaking process that could move marijuana from Schedule I to Schedule III under the Controlled Substances Act.

DOT responded the next day with a straightforward message: nothing had changed for transportation drug testing. Marijuana remained Schedule I, and DOT-regulated safety-sensitive employees remained subject to marijuana testing under existing rules.

Effective April 28, 2026, the Drug Enforcement Administration issued a final rule placing FDA-approved drug products containing marijuana, along with marijuana and marijuana products subject to qualifying state medical-marijuana licenses, into Schedule III. At the same time, the government moved forward with a separate process that would more broadly transfer marijuana from Schedule I to Schedule III. Formal hearings on that proposal ran from June 29 through July 15.

The federal government has therefore taken a Schedule III step involving medical marijuana while the broader question of marijuana’s classification remains pending.

Rescheduling also does not mean legalization. Schedule III substances remain controlled substances under federal law. Moving marijuana to Schedule III changes its federal classification, but it does not automatically make marijuana lawful to use, turn state-authorized medical marijuana into a federally recognized prescription, or eliminate federal workplace drug-testing requirements.

For DOT-regulated employers, the practical question is what rescheduling means for workplace drug testing.

Why Rescheduling Does Not End DOT Marijuana Testing

DOT drug-testing rules cover approximately 6.5 million employees performing safety-sensitive functions in trucking, aviation, rail, public transit, pipelines, maritime transportation and other regulated transportation operations.

If marijuana moves out of Schedule I, does DOT lose its ability to test for it?

The Department points to the Omnibus Transportation Employee Testing Act of 1991. DOT has told Congress that the law gives the Secretary of Transportation authority to test for controlled substances when their use poses a transportation-safety risk. That authority is not expressly limited to substances in Schedules I and II.

Moving marijuana to Schedule III, therefore, would not by itself eliminate DOT’s statutory authority to require marijuana testing.

The implementation question is more complicated.

DOT’s testing program works in conjunction with the Department of Health and Human Services’ Mandatory Guidelines for Federal Workplace Drug Testing Programs and HHS-certified laboratories. HHS currently includes marijuana on the authorized federal drug-testing panel, but portions of the federal testing framework are tied to Schedule I and II substances. DOT has acknowledged the issue and has coordinated with HHS over the potential impact of rescheduling on DOT testing and HHS-certified laboratories.

That leaves two related questions: Does DOT have authority to continue requiring marijuana testing? And will the federal testing framework need to change to support that testing after broader rescheduling?

DOT has affirmatively stated its position on the first. The second may require additional regulatory or administrative action.

Medical Marijuana Does Not Excuse A Positive DOT Test

DOT guidance also addresses what an MRO should do when an employee attributes a positive marijuana test to marijuana obtained through a state medical-marijuana program.

DOT regulations generally require an MRO to verify a confirmed marijuana positive unless the employee establishes a legitimate medical explanation. A legally valid prescription consistent with the Controlled Substances Act can potentially provide one.

A state medical-marijuana authorization does not.

DOT explains that state-dispensed marijuana is not FDA approved and, without FDA approval, cannot be prescribed as a controlled substance. A medical-marijuana card, physician recommendation or certification, or dispensary record or receipt does not satisfy DOT’s requirement for a legitimate medical explanation.

Return to the truck driver who tested positive. The driver may have followed state law, received a physician’s recommendation and purchased marijuana from a licensed dispensary. The MRO still cannot verify the positive DOT test as negative based on that documentation.

For transportation employers, this is a key distinction: Schedule III status and a federally valid prescription are two different things.

FMCSA Medical Qualification Raises A Separate Question

For commercial drivers, drug testing is only part of the equation. Drivers also must satisfy Federal Motor Carrier Safety Administration medical-qualification requirements.

FMCSA guidance has long said that a driver who uses marijuana cannot satisfy federal medical-qualification standards, even when a licensed medical practitioner recommends it, because marijuana is a Schedule I controlled substance. That guidance predates the federal government’s April 2026 Schedule III action.

The underlying regulation, however, treats Schedule I substances differently from substances in Schedules II through V.

Under 49 C.F.R. § 391.41(b)(12), Schedule I drug use is prohibited. For certain other controlled substances, the regulation contains a prescription exception when a licensed medical practitioner who is familiar with the driver’s medical history advises that the substance will not adversely affect the driver’s ability to operate a commercial motor vehicle safely.

That raises a question FMCSA may need to address more directly: How should FMCSA’s medical-qualification framework apply to marijuana products that are no longer classified in Schedule I?

The answer remains unsettled. DOT’s drug-testing guidance does not resolve that question. It establishes that state medical-marijuana authorization does not become a federally valid prescription simply because marijuana moves into Schedule III.

Employers therefore should avoid assuming that Schedule III permits medical marijuana use by commercial drivers or that FMCSA’s existing analysis will remain unchanged.

What About Recreational Marijuana?

DEA’s April action did not transfer marijuana sold under state recreational-marijuana laws into Schedule III. The broader federal rescheduling proceeding remains separate.

State legalization also does not determine what DOT permits in safety-sensitive transportation positions. An employee may engage in conduct permitted under state marijuana law while remaining subject to federal restrictions because of a safety-sensitive transportation position.

For multistate employers, that means dramatically different state marijuana laws can exist alongside the same federal transportation requirements.

What Should Transportation Employers Do Now?

Employers should continue their DOT drug-testing programs under existing requirements. Federal rescheduling activity does not provide a basis for suspending marijuana testing or changing how employers respond to verified DOT marijuana positives.

HR, safety and compliance teams should also understand that medical authorization under state law does not provide an MRO with a basis to reverse a positive DOT marijuana test.

Motor carriers should separately watch FMCSA’s medical-qualification guidance. Its existing marijuana guidance relies on marijuana’s Schedule I classification, while the underlying regulation treats certain Schedule II through V substances differently.

Employers should also watch more than DEA. DEA determines marijuana’s classification under the Controlled Substances Act, but DOT, HHS and individual transportation agencies such as FMCSA determine how that classification operates within federal transportation programs.

That may be the most important lesson for transportation employers. DEA may decide where marijuana belongs on the federal drug schedules. DOT and its agencies still determine what that classification means on the road, in the cockpit and across the rest of the nation’s transportation system.

For transportation employers, rescheduling is the beginning of the analysis, not the end.